zhibo/android-app/app/src/main/java/com/example/livestreaming/ConversationMessagesAdapter.java

package com.example.livestreaming;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.DiffUtil;
import androidx.recyclerview.widget.ListAdapter;
import androidx.recyclerview.widget.RecyclerView;

import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Locale;

public class ConversationMessagesAdapter extends ListAdapter<ChatMessage, RecyclerView.ViewHolder> {

    private static final int TYPE_INCOMING = 1;
    private static final int TYPE_OUTGOING = 2;

    private static final SimpleDateFormat TIME_FORMAT = new SimpleDateFormat("HH:mm", Locale.getDefault());

    public ConversationMessagesAdapter() {
        super(DIFF);
    }

    @Override
    public int getItemViewType(int position) {
        ChatMessage msg = getItem(position);
        if (msg == null) return TYPE_INCOMING;
        String u = msg.getUsername();
        return "我".equals(u) ? TYPE_OUTGOING : TYPE_INCOMING;
    }

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        if (viewType == TYPE_OUTGOING) {
            View v = inflater.inflate(R.layout.item_conversation_message_outgoing, parent, false);
            return new OutgoingVH(v);
        }
        View v = inflater.inflate(R.layout.item_conversation_message_incoming, parent, false);
        return new IncomingVH(v);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        ChatMessage msg = getItem(position);
        if (holder instanceof IncomingVH) {
            ((IncomingVH) holder).bind(msg);
        } else if (holder instanceof OutgoingVH) {
            ((OutgoingVH) holder).bind(msg);
        }
    }

    static class IncomingVH extends RecyclerView.ViewHolder {
        private final TextView nameText;
        private final TextView msgText;
        private final TextView timeText;

        IncomingVH(@NonNull View itemView) {
            super(itemView);
            nameText = itemView.findViewById(R.id.nameText);
            msgText = itemView.findViewById(R.id.messageText);
            timeText = itemView.findViewById(R.id.timeText);
        }

        void bind(ChatMessage message) {
            if (message == null) return;
            nameText.setText(message.getUsername() != null ? message.getUsername() : "");
            msgText.setText(message.getMessage() != null ? message.getMessage() : "");
            timeText.setText(TIME_FORMAT.format(new Date(message.getTimestamp())));
        }
    }

    static class OutgoingVH extends RecyclerView.ViewHolder {
        private final TextView msgText;
        private final TextView timeText;

        OutgoingVH(@NonNull View itemView) {
            super(itemView);
            msgText = itemView.findViewById(R.id.messageText);
            timeText = itemView.findViewById(R.id.timeText);
        }

        void bind(ChatMessage message) {
            if (message == null) return;
            msgText.setText(message.getMessage() != null ? message.getMessage() : "");
            timeText.setText(TIME_FORMAT.format(new Date(message.getTimestamp())));
        }
    }

    private static final DiffUtil.ItemCallback<ChatMessage> DIFF = new DiffUtil.ItemCallback<ChatMessage>() {
        @Override
        public boolean areItemsTheSame(@NonNull ChatMessage oldItem, @NonNull ChatMessage newItem) {
            return oldItem.getTimestamp() == newItem.getTimestamp();
        }

        @Override
        public boolean areContentsTheSame(@NonNull ChatMessage oldItem, @NonNull ChatMessage newItem) {
            return oldItem.getTimestamp() == newItem.getTimestamp();
        }
    };
}